diff options
Diffstat (limited to 'activerecord/lib/active_record/aggregations.rb')
| -rw-r--r-- | activerecord/lib/active_record/aggregations.rb | 38 |
1 files changed, 22 insertions, 16 deletions
diff --git a/activerecord/lib/active_record/aggregations.rb b/activerecord/lib/active_record/aggregations.rb index 5a8addc4e4..3db8e0716b 100644 --- a/activerecord/lib/active_record/aggregations.rb +++ b/activerecord/lib/active_record/aggregations.rb @@ -10,9 +10,9 @@ module ActiveRecord # Active Record implements aggregation through a macro-like class method called +composed_of+ # for representing attributes as value objects. It expresses relationships like "Account [is] # composed of Money [among other things]" or "Person [is] composed of [an] address". Each call - # to the macro adds a description of how the value objects are created from the attributes of - # the entity object (when the entity is initialized either as a new object or from finding an - # existing object) and how it can be turned back into attributes (when the entity is saved to + # to the macro adds a description of how the value objects are created from the attributes of + # the entity object (when the entity is initialized either as a new object or from finding an + # existing object) and how it can be turned back into attributes (when the entity is saved to # the database). # # class Customer < ActiveRecord::Base @@ -46,7 +46,7 @@ module ActiveRecord # # def <=>(other_money) # if currency == other_money.currency - # amount <=> amount + # amount <=> other_money.amount # else # amount <=> other_money.exchange_to(currency).amount # end @@ -71,7 +71,7 @@ module ActiveRecord # Now it's possible to access attributes from the database through the value objects instead. If # you choose to name the composition the same as the attribute's name, it will be the only way to # access that attribute. That's the case with our +balance+ attribute. You interact with the value - # objects just like you would any other attribute, though: + # objects just like you would with any other attribute: # # customer.balance = Money.new(20) # sets the Money value object and the attribute # customer.balance # => Money value object @@ -86,6 +86,12 @@ module ActiveRecord # customer.address_street = "Hyancintvej" # customer.address_city = "Copenhagen" # customer.address # => Address.new("Hyancintvej", "Copenhagen") + # + # customer.address_street = "Vesterbrogade" + # customer.address # => Address.new("Hyancintvej", "Copenhagen") + # customer.clear_aggregation_cache + # customer.address # => Address.new("Vesterbrogade", "Copenhagen") + # # customer.address = Address.new("May Street", "Chicago") # customer.address_street # => "May Street" # customer.address_city # => "Chicago" @@ -101,8 +107,8 @@ module ActiveRecord # ActiveRecord::Base classes are entity objects. # # It's also important to treat the value objects as immutable. Don't allow the Money object to have - # its amount changed after creation. Create a new Money object with the new value instead. This - # is exemplified by the Money#exchange_to method that returns a new value object instead of changing + # its amount changed after creation. Create a new Money object with the new value instead. The + # Money#exchange_to method is an example of this. It returns a new value object instead of changing # its own values. Active Record won't persist value objects that have been changed through means # other than the writer method. # @@ -119,7 +125,7 @@ module ActiveRecord # option, as arguments. If the value class doesn't support this convention then +composed_of+ allows # a custom constructor to be specified. # - # When a new value is assigned to the value object the default assumption is that the new value + # When a new value is assigned to the value object, the default assumption is that the new value # is an instance of the value class. Specifying a custom converter allows the new value to be automatically # converted to an instance of value class if necessary. # @@ -187,7 +193,8 @@ module ActiveRecord # * <tt>:converter</tt> - A symbol specifying the name of a class method of <tt>:class_name</tt> # or a Proc that is called when a new value is assigned to the value object. The converter is # passed the single value that is used in the assignment and is only called if the new value is - # not an instance of <tt>:class_name</tt>. + # not an instance of <tt>:class_name</tt>. If <tt>:allow_nil</tt> is set to true, the converter + # can return nil to skip the assignment. # # Option examples: # composed_of :temperature, :mapping => %w(reading celsius) @@ -216,7 +223,7 @@ module ActiveRecord reader_method(name, class_name, mapping, allow_nil, constructor) writer_method(name, class_name, mapping, allow_nil, converter) - create_reflection(:composed_of, part_id, options, self) + create_reflection(:composed_of, part_id, nil, options, self) end private @@ -235,16 +242,15 @@ module ActiveRecord def writer_method(name, class_name, mapping, allow_nil, converter) define_method("#{name}=") do |part| + klass = class_name.constantize + unless part.is_a?(klass) || converter.nil? || part.nil? + part = converter.respond_to?(:call) ? converter.call(part) : klass.send(converter, part) + end + if part.nil? && allow_nil mapping.each { |pair| self[pair.first] = nil } @aggregation_cache[name] = nil else - unless part.is_a?(class_name.constantize) || converter.nil? - part = converter.respond_to?(:call) ? - converter.call(part) : - class_name.constantize.send(converter, part) - end - mapping.each { |pair| self[pair.first] = part.send(pair.last) } @aggregation_cache[name] = part.freeze end |